1. Field of the Invention
The present invention relates generally to geared mechanical linkages for motor driven device components, and more particularly to a compliant worm gear and worm gear bracket for the engagement of a motor with a helical gear within a tape drive system
2. Description of the Prior Art
The compliant worm gear and worm gear support bracket is particularly adapted for controlling the movement of a read/write tape head within a tape drive device, however, it is applicable and useful within generalized light duty motor drive systems. The preexisting geared linkage, to which the present invention is an improvement, includes a motor, a worm gear having an extended shaft, and a separate flexible, cylindrical coupler that joins the motor shaft to the worm gear shaft. A support bracket having a leaf spring controlled bearing disposed within the bracket is utilized to rotatably support the worm gear shaft, such that the worm gear is held in a driving engagement with a helical gear. The helical gear is threadably engaged upon a stationary, threaded rod and also operably engaged within a tape drive head support structure. The linkage functions such that rotation of the worm gear causes rotation of the helical gear, and rotation of the helical gear causes lateral (axial) movement of the helical gear along the stationary threaded rod, resulting in corresponding axial movement of the tape drive head support structure. Further details of this prior art geared linkage are provided herebelow with the aid of FIG. 1.
The present invention constitutes an improvement upon the prior art geared linkage described above, in that the flexible, cylindrical coupler previously utilized to engage the motor shaft with the worm gear shaft is eliminated. The shaft of the worm gear of the present invention is composed of a sufficiently flexible material to operably correct minor misalignments between the worm gear shaft direction and the motor shaft direction, and to accommodate minor misalignments between the worm gear and the helical gear interface, such that the flexible coupler of the prior art is no longer required. Additionally, the improved worm gear support bracket of the present invention includes a robust, flat, leaf spring which provides sufficient lateral force against the worm gear shaft to maintain a driving engagement between the worm gear and the helical gear. The leaf spring has improved stiffness in the two other in-plane directions of movement (axial and vertical) to provide improved support for the worm gear shaft, while axial loads on the shaft are supported by the motor bearings. The worm gear support bracket also includes a worm gear shaft engagement bushing which provides a support for the worm gear shaft against the helical gear while facilitating a simplified assembly of the geared linkage. Two bushing embodiments are provided; a C-shaped bushing and a cylindrical bushing, each having differing properties and advantages.
It is an advantage of the mechanical linkage of the present invention that it has fewer parts and is easier to assemble than the prior art linkage.
It is another advantage of the mechanical linkage of the present invention that it is less expensive than the prior art mechanical linkage.
It is a further advantage of the mechanical linkage of the present invention that it includes a worm gear shaft support bracket that is compliant in one direction to urge the worm gear into engagement with a helical gear, and stiff in other directions to prevent backlash and disengagement of the worm gear with the helical gear.
It is yet another advantage of the mechanical linkage of the present invention that it utilizes a simple, effective C-shaped bushing embodiment that holds the worm gear in operative engagement with the helical gear, allowing easy assembly.
It is yet a further advantage of the mechanical linkage of the present invention that it includes a drive motor shaft engagement bore formed in the distal end of the worm gear shaft to create a frictional interference fit between the drive motor shaft and the worm gear shaft.
It is still another advantage of the mechanical linkage of the present invention that it includes a cylindrical bushing embodiment that more securely engages the worm gear shaft with the support bracket.
It is an advantage of the tape drive of the present invention that it includes a tape head actuator including a mechanical linkage that has fewer parts and is easier to assemble than the prior art linkage.
It is another advantage of the tape drive of the present invention that it includes a tape head actuator including a mechanical linkage that is less expensive than the prior art mechanical linkage.
It is a further advantage of the tape drive of the present invention that it includes a tape head actuator including a mechanical linkage that includes a worm gear shaft support bearing that is compliant in one direction to urge the worm gear into engagement with a helical gear, and stiff in other directions to prevent backlash and disengagement of the worm gear with the helical gear.
It is yet another advantage of the tape drive of the present invention that it includes a tape head actuator including a mechanical linkage that utilizes a simple, effective C-shaped bushing embodiment that holds the worm gear in operative engagement with the helical gear.
It is yet a further advantage of the tape drive of the present invention that it includes a tape head actuator including a mechanical linkage that includes a drive motor shaft engagement bore formed in the distal end of the worm gear shaft to create a frictional interference fit between the drive motor shaft and the worm gear shaft.
It is still another advantage of the tape drive of the present invention that it includes a tape head actuator including a mechanical linkage that it includes a cylindrical bushing embodiment that more securely engages the worm gear shaft with the support bracket.